Internal circulation fluidized bed (ICFB) combustion system and method of operation thereof

An internal circulation fluidized bed combustion system for effecting the combustion of materials comprising:

• a. a fluidized bed combustor including a fluidized bed, an air distributor means and a sloped baffle means, said fluidized bed being composed of bed solids, said air distributor means being operative to inject air into said fluidized bed to create a plurality of controlled fluidizing velocity zones within said fluidized bed, one of said plurality of controlled fluidizing velocity zones embodying a relatively high fluidizing velocity and a relatively low bed density, another one of said plurality of controlled fluidizing velocity zones embodying a relatively low fluidizing velocity and a relatively high bed density, said air distributor means further being sloped in a downwardly direction from said another one of said plurality of controlled fluidizing velocity zones to said one of said plurality of controlled fluidizing velocity zones in order to enhance the movement of inerts, tramp materials, clinkers as well as large diameter solids through said fluidized bed combustor, said sloped baffle means having a first portion extending below the level of said fluidized bed so as to thereby bound a portion of said one of said plurality of controlled fluidizing velocity zones of said fluidized bed and having a second portion thereof extending above said one of said plurality of controlled fluidizing velocity zones of said fluidized bed, said sloped baffle means being operative to promote the growth of gas bubbles within said one of said plurality of controlled fluidizing velocity zones in order to thereby maximize the momentum within said one of said plurality of controlled fluidizing velocity zones of the gas bubbles and bed solids upwards along said sloped baffle means until the end of said second portion thereof is reached thereby such that the momentum possessed by the gas bubbles and bed solids coupled with the force created by the bursting of the gas bubbles as the gas bubbles reach the end of said second portion of said sloped baffle means is sufficient to project bed solids from said one of said plurality of controlled fluidizing velocity zones to said another one of said plurality of controlled fluidizing velocity zones whereupon the projected bed solids rain down on said another one of said plurality of controlled fluidizing velocity zones;
• b. material feed means for introducing the material to be combusted into said fluid bed combustor above said another one of said plurality of controlled fluidizing velocity zones whereupon bed solids projected from said one of said plurality of controlled fluidizing velocity zones rain down on the material so introduced thereby covering the material and concomitantly initiating the drying thereof;
• and
• c. removal means cooperatively associated with said fluidized bed and operative to effect the separation and subsequent removal from said fluidized bed combustor of inerts, tramp materials, clinkers as well as large diameter solids entrained within the material introduced into said fluidized bed combustor by means of said material feed means, said removal means including a drain, classification chamber means cooperatively associated with said drain and valve means cooperatively associated with both said drain and said classification chamber means, said drain having one end thereof located in juxtaposed relation to said air distributor means for receiving inerts, tramp materials, clinkers as well as large diameter solids therefrom, said classification chamber means being operative to effect the segregation from the inerts, tramp materials, clinkers as well as large diameter solids of the fines entrained therewith, said valve means being operative to effect the movement of the inerts, tramp materials, clinkers as well as large diameter solids from said drain to said classification chamber means and to effect the discharge from said removal means at a first location thereof of the fines and at a second location thereof of the inerts, tramp materials, clinkers as well as large diameter solids after the fines have been removed therefrom.

A method of operating a fluidized bed combustion system to effect therewith the combustion of material comprising the steps of:

• a. providing a fluidized bed combustor embodying a fluidized bed composed of bed solids;
• b. injecting air into the fluidized bed to establish at a first location thereof a first controlled fluidizing velocity zone having a relatively high fluidizing velocity and a relatively low bed density;
• c. injecting air into the fluidized bed to establish at a second location thereof a second controlled fluidizing velocity zone having a relatively low fluidizing velocity and relatively high bed density;
• d. creating a circulation of the bed solids within the fluidized bed;
• e. promoting the growth of gas bubbles within the first controlled fluidizing velocity zone to maximize the upward momentum of the gas bubbles and bed solids within the first controlled fluidizing velocity zone;
• f. projecting bed solids from the first controlled fluidizing velocity zone to the second controlled fluidizing velocity zone as a consequence of the upward movement of the gas bubbles and bed solids within the first controlled fluidizing velocity zone coupled with the force of the gas bubbles bursting whereupon the projected bed solids rain down upon the second controlled fluidizing velocity zone;
• g. introducing into the fluidized bed combustor above the second controlled fluidizing velocity zone to be combusted therewithin the material having inerts, tramp materials, clinkers as well as large diameter solids entrained therewith;
• h. covering the material so introduced into the fluidized bed combustor with bed solids that rain down thereupon after being projected from the first controlled fluidizing velocity zone to the second controlled fluidizing velocity zone;
• i. effecting the drying of the material so introduced followed by the subsequent combustion thereof;
• j. establishing a downward slope between the second controlled fluidizing velocity zone and the first controlled fluidizing velocity zone in order to enhance the movement of the inerts, tramp materials, clinkers as well as large diameter solids within the fluidized bed combustor;
• k. providing a device for receiving the inerts, tramp materials, clinkers as well as large diameter solids from the first controlled fluidizing velocity zone;
• l. effecting the segregation of the inerts, tramp materials, clinkers as well as large diameter solids from the fines entrained therewith during the passage thereof through the device;
• m. effecting thereafter the discharge of the fines at a first location;
• and
• n. effecting thereafter the discharge of the inerts, tramp materials, clinkers as well as large diameter solids at a second location.